Computer systems generally utilize auxiliary memory storage devices having media on which data can be written and from which data can be read for later use. A direct access storage device (disk drive) incorporating rotating magnetic disks is commonly used for storing data in magnetic form on the disk surfaces. Data is recorded on concentric, radially spaced tracks on the disk surfaces. Magnetic heads including magnetoresistance (MR) sensors are then used to read data from the tracks on the disk surfaces.
Prior Art FIG. 1 illustrates a magnetic head 100 adapted to accommodate traditional MR sensors. As shown, a pair of shields 102 is provided with an MR sensor 104 positioned therebetween. Further, such shields 102 have a rectangular configuration defined by parallel side edges. In use, the magnetic head 100 is adapted to be positioned over a magnetic recording disk 106 with an air bearing surface therebetween.
Prior Art FIG. 2 is a cross-sectional view taken along line 2—2 of FIG. 1 again showing the shields 102 with the MR sensor 104 therebetween. As shown in FIG. 2, the MR sensor 104 is maintained between the shields 102 at a lower extent thereof at a point immediately adjacent to the magnetic recording disk 106.
As is well known, the magnetic recording disk 106 is populated with magnetic flux that is representative of stored data. In use, a current is conventionally applied to the MR sensor 104, and a voltage is monitored across the MR sensor 104. Such voltage fluctuates as a function of a resistance of the MR sensor 104 which, in turn, fluctuates as a function of the particular magnetic fields that are present on the magnetic recording disk 106 as result of the flux. By this design, the MR sensor 104 may be used to read the contents of the magnetic recording disk 106 as the magnetic head 100 is moved.
Prior Art FIGS. 2-1 and 2-2 are cross-sectional views taken along lines 2-1 and 2—2 of FIG. 2 showing the current flow in the MR sensor 104 and the magnetic flux of the magnetic recording disk 106, respectively. As shown, the aforementioned current flow resides in a particular plane 200. Further, the magnetic flux 202 that is present on the magnetic recording disk 106 is parallel with such plane 200 of current flow. It should be noted that such parallel relationship between the magnetic flux 202 and the current flow plane 200 is required for traditional MR sensors to operate properly.
Recently, various institutions have recognized a new type of semiconductor material that exhibits extraordinary magnetoresistance (EMR). This is accomplished by embedding a Au metal within semiconductor material (e.g. InSb). More information on such EMR materials may be found with reference to the following article: Solin et al., “Enhanced Room-Temperature Magnetoresistance in Inhomogeneous Narrow-Gap Semiconductors,” SCIENCE Journal, 1 Sep. 2000, Vol. 289, Page 1530. Further reference may be made to U.S. Pat. No.: 5,965,283 which is incorporated herein by reference.
While such EMR material has been recognized as a candidate for use in storage technology, there have currently been no advancements in actual implementations of such application. One suggested reason for such lack in the art is the different characteristics exhibited by EMR material with respect to traditional materials used with MR sensors 104. In particular, the MR sensors 104 can not simply be substituted with an EMR sensor.
As mentioned before, a field from recorded bits on a magnetic media flows in the plane of a sensor material in the case of giant MR or magnetic tunnel junction sensors. In sharp contrast, the field from the recorded bits needs to be perpendicular to the plane of the sensor material to obtain the extra-ordinary magnetoresistive effect when using EMR sensors.
One prior art solution is disclosed by Solin et al. in the “Digests of the Magnetic Recording Conference,” 2001, paper C-5. Such solution provides a horizontal EMR sensor. However, this configuration is not suitable for current manufacturing methods, and is very difficult to construct.
There is thus a need for a practical application of EMR material in the storage technology domain.